THE STRUCTURES OF PITCHER PLANTS. 



very wide, and the stalk touches the platform. The pitchers of an 

 old plant, however, have only very slight ridges to represent the 

 wings, they are prolonged into conical funnels, and are bent on the stalk 

 in the direction opposite to that of the young pitchers, whilst the stalk 

 does not approach the side of the pitcher. Their structure is likewise 

 altered in that the pitchers of the young plant are soft and easily 

 withered, whilst those of the old are hard and coriaceous, and are 

 scarcely altered either in colour or shape by prolonged drying. Diges- 

 tive powers in the latter can hardly be said to exist, and the pitchers 

 seem to have degenerated into mere receptacles of water. 



On this most interesting point I have the following information 

 from Messrs. Veitch, the well-known growers of pitcher plants : — 

 " Flowers and pitchers are never borne on the same plant a,t the same 

 time, the production of the latter always preceding that of the former, 

 and when the plant is in a condition to produce flowers the pitchers 

 become abortive and cease to be formed. The leaves of seedlings and 

 young plants form their pitcher appendages from the very first. In 

 young plants the winged side of the pitcher is turned towards the petiole, 

 the lamina or lid being of course opened on the opposite side. As the 

 plants increase in age and strength, the newly formed pitchers are 

 elongated, and finally become curved something like the horn of an ox ; 

 their position with reference to the petiole being then changed, the 

 winged side being turned away from it. During these gradual changes 

 the wings cease to be developed. When the plants are several feet high, 

 and are in a condition to bear flowers, the pitchers cease to be formed." 



It is clear, therefore, that the pitchers and their digestive processes 

 are useful for the development of the reproductive function of the 

 plant. This is also shown by the fact, stated to me by growers, that if it 

 is wished that a plant of Sarracenia should continue to grow pitchers, 

 its flower must be nipped off before it is impregnated. 



These changes take place in the pitchers of other varieties of Nepen- 

 thes apparently sometimes independently of age, but rather in consequence 

 of an abundance of food and its being easily obtained. Thus the pitchers 

 of N. gracilis and N. distillatoria are quite wingless, but have always very 

 active digestion. The real significance of these changes can be determined 

 only by a study of the plants under their natural conditions, and when 

 this has been done I have little doubt that they will afford very striking 

 illustrations of the modification of structure by the influence of 

 surrounding circumstances. Another noteworthy matter in the general 

 structure of the pitchers is the lid. Sometimes it covers the mouth com- 

 pletely, as in N. distillatoria, N. phyllamphora, N. Khasyoma, &c. In other 

 cases, it either stands erect, as in N. Rafflesiana, or covers the mouth 

 very imperfectly. "When it covers the mouth the pitcher is nearly always 

 bottle-shaped, having a very distinct constriction about its middle, which 

 marks the abrupt cessation of the secreting surface. In such cases the 

 amount of secretion is always small, but its action is very powerful, and 

 the lid covering the pitcher is evidently for the purpose of excluding rain. 

 Mr. Albert Ratcliffe, a very successful grower and a minute observer, 

 informs me that the lid of N. distillatoria closes over the mouth towards 

 evening. This may be to prevent the ingress of nocturnal insects too 

 large for its digestive powers. When the lid is erect, the glandular surface 

 comes up close to the lip of the pitcher, the secretion is large in quantity 

 and slow in action, and the addition of rain-water does not seem of much 

 consequence. This is well seen in N. Rafflesiana and in N. ampullacea 

 vittata. These differences arc sure to be dependent upon some conditions 

 peculiar to the native habitat of the plant, or to the food of which it 

 partakes. 



(To be continued.) 



